Question: Simplify the following expression: $k = \dfrac{5yx}{zx + 2yx} - \dfrac{2yx - zx}{zx + 2yx}$ You can assume $x,y,z \neq 0$.
Solution: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{5yx - (2yx - zx)}{zx + 2yx}$ $k = \dfrac{3yx + zx}{zx + 2yx}$ The numerator and denominator have a common factor of $x$, so we can simplify $k = \dfrac{3y + z}{z + 2y}$